/// <summary>
/// Create the download controller for this file
/// </summary>
/// <param name="file"></param>
public FileDownloadController(IFile file, IBlobCache cache = null)
{
File = file;
Cache = cache ?? Blobs.LocalStorage;
// Download or update the file.
DownloadOrUpdate = ReactiveCommand.Create();
var hasCachedValue = DownloadOrUpdate
.SelectMany(_ => File.GetCacheCreateTime(Cache))
.Select(dt => dt.HasValue)
.Publish().RefCount();
var cacheUpdateRequired = hasCachedValue
.Where(isCached => isCached)
.SelectMany(_ => File.CheckForUpdate(Cache))
.Where(isNewOneEB => isNewOneEB)
.Select(_ => default(Unit))
.Publish();
cacheUpdateRequired.Connect();
var firstDownloadRequired = hasCachedValue
.Where(isCached => !isCached)
.Select(_ => default(Unit));
var downloadInProgress = new Subject <bool>();
var downloadRequired =
Observable.Merge(cacheUpdateRequired, firstDownloadRequired)
.Do(_ => downloadInProgress.OnNext(true));
var downloadSuccessful =
downloadRequired
.LimitGlobally(goSeq => goSeq
.WriteLine("Starting download...")
.SelectMany(_ => Download())
.SelectMany(data => File.SaveFileInCache(data.Item1, data.Item2, Cache))
.WriteLine(" Done download and cache insert"), _gLimit)
.Finally(() => downloadInProgress.OnNext(false))
.Do(_ => downloadInProgress.OnNext(false))
.Catch(Observable.Empty <Unit>())
.Select(_ => true)
.Replay(1);
downloadSuccessful.Connect();
FileDownloadedAndCached = downloadSuccessful.Select(_ => default(Unit));
// When we are downloading, set the IsDownloading to true.
downloadInProgress
.ToProperty(this, x => x.IsDownloading, out _isDownloading, false);
// Track the status of the download
// Note the concatenate when we combine - we very much want this to run
// in order, no matter what latencies get caught up in the system.
// This must be run when we are subscribed to, hence the defer.
var initiallyCached = Observable.Defer(() => File.GetCacheCreateTime(Cache)
.Delay(TimeSpan.FromMilliseconds(50))
.Select(dt => dt.HasValue));
Observable.Concat(initiallyCached, downloadSuccessful)
.WriteLine(v => string.Format("We are doing the IsDownloaded to {0}", v))
.ToProperty(this, x => x.IsDownloaded, out _isDownloaded, false);
}